Lamp-globe



'2 sheetse-sheet 1. G.W. BALLOU 8a A. SHAVER.

LAMP GLOBE.

(No Model.)

mvmrons H Patented Nov. 10, 1896 W XMZf A TTORNEK 2 m h s .m. a e h s RE V A E 8 m &m G UP. M LA LL A B W G a d o M 0 W Patented Nov. 10, 1896.

Fig: 7.

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ATTORNEY WITNESSES UNITED STATES PATENT OFFICE.

GEORGE WILLIAM BALLOU, OF NE\V YORK, N. Y. AND AUGUSTUS SEAVER, OFBOSTON, MASSACHUSETTS, ASSIGNORS TO THE UNITED STATES OF NEW YORK.

LAM P-GLOBE.

SPECIFICATION forming part of Letters Patent No. 570,896, dated November10, 1896.

Application filed June 24, 1896.

To all whom, it may concern.-

Be it known that we, GEORGE WILLIAM BALLOU, a resident of New York,inthe county of New York and State of New York, and AUGUSTUS SEAVER, aresident of Boston, in the county of Suffolk and State of Massachusetts,citizens of the United States, have invented certain new and usefulImprovements in Lamp-Globes, of which the following is a specification.

Our invention relates to glass globes of prismatic type for envelopingelectric, gas, and other lights used for illuminating streets,dwellings, &c.

The object of our invention is first to devisea process or method ofmakingsuch globes,

-whereby we are enabled to produce each globe, of spherical orspheroidal form, in one entire piece of glass, with perfect interiorprisms, the outer surface being smooth.

Another object is the production of such a globe wherein the interiorprisms, longitudinal of the globe, are alternate thick and thinperiscopic convex lenses, the horizontal section of the former beinginterior convex and that of the latter interior concave, the curvedfaces of the prisms pointing directly toward the center of the globe andof the source of light.

By our new process or method of manufacture we are enabled to producethe globes and prisms under conditions which preserve the fullesttransparency of that portion of the glass which forms the exterior ormain shell of the globe, and at the same time augment the smoothness andtransparency of the side surfaces of the prisms, and also to make theprisms very close together, very distinct in outline, and with smoothand brilliant surfaces, and with the edges drawn sharp, so that theglobe approximates cut glass in appearance. This said brilliantappearance of the globe results from the drawing of the glass (byblowing) along or away from the edges of the prisms, which said edgeshave been previously chilled in the first step of the process, andremain so throughout, so that sharpedged prisms are insured, and so thatin completing the globe by blowing all superficial Serial No. 596,690.(No model.)

mold marks are obliterated from the surfaces of the globe. the leastpossible resistance to the passage through it of the rays of light, andthe prisms or lens-formations of the globe, by reflection andrefraction, increase the apparent sizeof the flame or light within theglobe and soften the light to the eyes of the observer and diffuse itwithout loss of illuminating-power, but

electric and other very strong lights the globe acts to increase theeffective general illuminating-power of the light, while at the sametime it tempers the light to the eyes.

e will now describe our invention in detail, in connection with theaccompanying drawings, which form a part of this specification, and inwhich- Figure l is a sectional elevation of the mold and plungeremployed in the first step of our process for forming the bloom or blankof glass from which the globe is formed. Fig. 2 is a sectional View ofthe plunger. Fig. 3 is a side elevation of the blank with theblowing-punty attached. Fig. 4 is a sectional elevation of theforming-mold, showing the globe, waste glass, and blowing-post in dottedlines. Fig. 5 is a sectional elevation of the globe. Fig. 6 is asectional plan view of the globe, and Fig. 7 is an enlarged sectionalperspective view of a portion of the body of the globe.

A represents a mold made in two parts a a, each formed with asemicylindrical cavity 1) h rounded and closed at the bottom, and Brepresents a substantially cylindrical plunger less in diameter than thecavity of the mold, tapered and rounded at its lower end and formed withlongitudinal ribs 0 0 around its circumference. These ribs are closetogether and the grooves or recesses cc are by preference brought tosharp points, but in some cases they may be rounded, as shown at theright of Fig. 9

for centering the plunger to the cavity of the O on the handle of theplunger, serves to limit the inward thrust of the plunger into Theglobe, therefore, presents with actual gain, and particularly with theat 0 which formation willslightly round out the opposite inclinedsurfaces of each rib. O C (J represent a guide-- mold, and said guide,in connection with stop the mold, so that a sufficient body of glasswill remain undisturbed in the bottom of the mold after the plunger hasbeen inserted.

In practice the two sections of the mold A will be closed and aproperquantity of molten glass will be poured therein, then the plunger B willbe forced down into the mold and into the molten glass and left toremain until the whole body of glass has become sufficiently cooled orset to be removed for blowing, and then the plunger will be carefullywithdrawn. 111 the interval of time the plunger remains in the glass,the prisms f, being partially isolated thin strips of glass, will havebecome chilled at their edges from contact with the plunger and colderthan the remainder of the glass. On being removed from the mold theoperator applies a cap and tube H H, usually termed a punty, to the openend of the blank and lifts the latter from the mold, and by twirlingforms the flange h in that portion of the blank which previouslysurrounded the plane portion 0 of the plunger above the grooves andribs. The blank is then placed in the shaping mold or form D and theblank is then blown to proper size, the same being reheated in theblowing process as often as required. The for1ning-m0ld is made in twosections adapted to be opened and closed, and at its open end is formedor provided with the annular beveled templet t', which perfects theflange h. In blowing, a surplus of glass forms a waste-bulb 11 which isto be broken away at the angle i from the per manent flange, which issubsequently cut or ground true. The reheating of the blank is externalto the partially-formed globe, so that at all times the edges of theprisms remain in a chilled or comparatively cool condition, and in theprocess of blowing and enlargement of the blank to the proper size theglass spreads like a soap-bubble and becomes thin between the prisms andvery smooth and transparent, and at the same time the prisms arestretched and the opposite inclined surfaces thereof are depleted ofglass and the prisms become slender, very regular, and smooth, while thechilled edges of the prisms become sharp and regular and conformperfectly to the curved outline of the completed globe. All surfaces ofthe completed globe thus become highlypolished, clear, and transparentto the extent of being nearly, if not quite, as brilliant as cut glassor as brilliant as the fracture of broken glass.

\Vhile we design to enlarge the spaces in the plunger, as shown at 0Fig. 2, and thus make the opposite sloping surfaces of the V- shapedprisms more concave than they would be if the surface were plane, we donotwi sh to be limited to this or any specific form of the grooves inthe plunger, for the degree of refraction and reflection of the prismsand intermediate concave lenses may be in this manner varied accordingto the size of the globe to be made and accordingto the particular kindof light with which the globes may be designed to be used.

The globe constructed as described comprises the outer smooth sphericalsurface f, the curved interior prisms or lenses f, and the intermediatethinner lenses f alternating the prismatic lenses f, which are each (invertical section of the globe) periscopic conveX lens, as shown in Fig.5, while the opposite inclined side surfaces of the prisms are eitherplane or concaved and merge into the thin lenses f so that each lens fbecomes substantially a plano-concave lens, as shown at 1 2 3, Fig. 7.The reflecting and refracting results are illustrated in Figs. 6 and 7,both within and outside of the globe. Looking through the globe at thelight the lines of vision cross at a point about midway be tween thesource of light and the edges of the prisms, so that naturally the flameor source of light is greatly magnified and also softened to the eyesand, reversely, the light is correspondingly diffused out into the roomor space to be lighted. The rays of light which strike the apex of eachprism are focused at a point away from the globe corresponding to theextent of surface exposed to the direct rays of light, and each slopingside surface of the prisms reflect the light to its neighboring inclinedsurface, and thence is refracted out into the room, while the lenses f(1 2 3) be tween the prisms diverge the rays of light horizontally andalso vertically, the latter owing to the general curved or sphericalformation of the body of the globe.

The horizontal divergence of the rays produced by the intermediatelenses may be increased or diminished by cutting the grooves in theplunger to a more or less blunt angle, as indicated at 0 Fig. 2.

lVe do not limit ourselves to any specific proportions, but for ordinaryincandescent electric lamps we find by experiment that for a globe fiveinches in transverse diameter and five and one-half inches long theblank should be four inches in diameter and five incheslong, and theglass three-sixteenths of an inch. thick to the base of the prisms.

Having thus described our invention, what we claim as new, and desire tosecure by Letters Patent, is

IIO

1. The method, or process, herein described of making glass prismaticglobes, which consists in first forming chilled prisms upon the innersurface of a hollow blank of glass, and then drawing the glass betweenthe prisms by blowing the blank to finished form; substantially as andfor the purposes set forth.

2. The method, or process, herein described of making glass prismaticglobes, which consists in first forming a blank of glass having asubstantially smooth exterior surface and a central cylindrical cavityformed with a series oflongitudinal prisms chilled at their edges fromcontact with a plunger, and then by successively blowing and externallyreheating the blank drawing the glass between the prisms and enlargingand fashioning the same to finished form; substantially as set forth.

3. As a new article of manufacture a prismatic spherical globe, made inone piece of glass, and having a smooth exterior surface and havinginterior alternate prisms and concave lenses which prisms and lenses arealso periscopic convex lenses from base to apex of the globe;substantially as described.

4:. As a new article of manufacture a prismatic spherical globe, open atone end only,

and made in one piece of glass, and havinga smooth exterior surface andhaving interior 15 alternate prisms and concave lenses which prisms andlenses are also periscopic convex lenses from base to apex of the globe;substantially as described.

GEORGE W'ILLIAM BALLOU. AUGUSTUS SEAVER. WVitnesses to signature ofGeorge William Ballou:

Wm'rnRoP Pom), H. A. WEST. \Vitnesses to signature of Augustus Seaver:

JOHN T. REYNOLDS, J os. LEWIS.

